In a league-wide memo obtained by CNN, the NFL outlines the screening and testing guidelines now in place. Coronavirus testing will commence at the start of training camps and last for two weeks. Results from those weeks of testing will dictate a move to test every other day.

The memo says that players are required to test for coronavirus twice before entering team facilities for the first time. Tests must be separated by at least 72 hours.

On Monday, Dr. Allen Sills, the NFL's chief medical officer, outlined the guidelines on a conference call with select media including ESPN.

If after two weeks of daily testing the results for all team members are at or below 5%, testing will shift to every other day.

"Our union has been pushing for the strongest testing and tracing protocols to keep our players safe," according to a statement from the NFL Players Association confirming the agreement.

"The testing protocols we agreed to are one critical factor that will help us return to work safely and gives us the best chance to play and finish the season."

Possibly zero preseason games

Also on Monday, the NFL offered the player's union the opportunity to play zero preseason games, according to a source familiar with the negotiations between the league and the union.

According to the source, the league started at four, which is the custom number of preseason games played per team. That offering then went down to two games, and then to none. The union has not accepted the offer, the source says.

"Precise points on the discussions between the NFL and NFLPA:

"1. NFL didn't offer or give up preseason games for us. They had the right to set those (or not) under the CBA already.

"2. NFL didn't "concede" on health and safety issues. We implemented the best protocols together.

"Of course our union had to advocate hard for all of these protections because everyone wants to ... start and - most importantly - finish a full season, but the fact is we all conceded to a virus that is still rampant in our country. Crassly put: no protections, no games, no $," Atallah wrote.

The players are being encouraged to wear "non-intrusive wearable sensor technology" that the league says will measure respiratory functions, heart rate, and sleep patterns, according to the document. Players are advised to utilize the offered antibody testing but will not be required to participate.

Team training camps are set to begin July 28.

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NFL and players union agree on daily Covid-19 testing to start training camps - CNN